It is known that the bleaching power of peroxidic bleaches such as perborates, percarbonates, persilicates and perphosphates can be improved such that the bleaching effect starts at lower temperatures, for example at or below 60.degree. C., by adding the precursors of bleaching peroxy acids, which are often referred to as bleach activators.
Many substances are known as bleach activators from the prior art. These are usually reactive organic compounds having an O-acyl or N-acyl group, which in alkaline solution, together with a source of hydrogen peroxide, form the corresponding peroxy acids.
Representative examples of bleach activators are N,N,N',N'-tetraacetylethylenediamine (TAED), glucose pentaacetate (GPA), xylose tetraacetate (TAX), sodium 4-benzoyloxybenzenesulfonate (SBOBS), sodium trimethylhexanoyloxybenzenesulfonate (STHOBS), tetraacetylglycoluril (TAGU), tetraacetylcyanic acid (TACA), di-N-acetyidimethylglyoxine (ADMG) and 1-phenyl-3-acetylhydantoin (PAH). Reference may be made, for example, to GB-A-836 988, GB-A-907 356, EP-A-0 098 129 and EP-A-0 120 591.
Over time, nitrilic bleach activators have gained in importance since they have proven to be extraordinarily bleaching-active. On perhydrolysis, these compounds probably form a peroxyimidic acid, which is the bleaching agent.
Such nitrilic bleach activators and their use as bleach activators in bleaches are described, for example, in EP 303 520, GB 802 035, U.S. Pat. No. 4,883,917, U.S. Pat. No. 5,478,356, U.S. Pat. No. 5,591,378, WO 9 606 912 and WO 9 640 661.